Monosilane or disilane derivatives and method for low temperature deposition of silicon-containing films using the same

ABSTRACT

This invention relates to silicon precursor compositions for forming silicon-containing films by low temperature (e.g., &lt;550° C.) chemical vapor deposition processes for fabrication of ULSI devices and device structures. Such silicon precursor compositions comprise at least a silane or disilane derivative that is substituted with at least one alkylhydrazine functional groups and is free of halogen substitutes.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation, filed under the provisions of 35 USC §120, ofU.S. patent application Ser. No. 10/683,501 filed Oct. 10, 2003, nowU.S. Pat. No. 7,579,496 issued Aug. 25, 2009. The entire disclosure ofsaid U.S. Pat. No. 7,579,496 is hereby incorporated herein by reference,for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to the formation ofsilicon-containing films in the manufacture of semiconductor devices,and more specifically to compositions and methods for forming suchfilms, e.g., films comprising silicon, silicon nitride (Si₃N₄),siliconoxynitride (SiO_(x)N_(y)), silicon dioxide (SiO₂), etc., lowdielectric constant (k) thin silicon-containing films, high k gatesilicate films and low temperature silicon epitaxial films.

DESCRIPTION OF THE RELATED ART

Silicon nitride (Si₃N₄) thin films are widely employed in themicroelectronic industry as diffusion barriers, etch-stop layers,sidewall spacers, etc.

Deposition of silicon nitride films by chemical vapor deposition (CVD)techniques is a highly attractive methodology for forming such films.CVD precursors currently used include bis(tert-butylamino)silane (BTBAS)or silane/ammonia, but such precursors usually require depositiontemperature higher than 600° C. for forming high quality Si₃N₄ films,which is incompatible with the next generation IC device manufacturing,where deposition temperature of below 500° C., and preferably about 450°C., is desired. Therefore, development of low-temperaturesilicon-containing CVD precursors is particularly desired.

Presently, hexachlorodisilane, Cl₃Si—SiCl₃, is being studied as acandidate precursor for low-temperature CVD formation of silicon nitridethin films upon reaction with ammonia gas. The drawbacks of usinghexachlorodisilane in CVD processes include: (i) formation of largeamount of NH₄Cl during the process, which leads to the particlecontamination and solid build-up in vacuum system and exhaust lines;(ii) possible chlorine incorporation in the chips, which couldsignificantly reduce their life time and long-term performance; and(iii) the reaction by-products are known to be explosive. It istherefore desirable to develop new chlorine-free precursors that can beused for low-temperature CVD formation of silicon nitride thin films.

SUMMARY OF THE INVENTION

The present invention relates generally to the formation ofsilicon-containing films, such as films comprising silicon, siliconnitride (Si₃N₄), siliconoxynitride (SiO_(x)N_(y)), silicon dioxide(SiO₂), etc., silicon-containing low k films, high k gate silicates, andsilicon epitaxial films, among which silicon nitride thin films arepreferred, in the manufacture of semiconductor devices, and morespecifically to compositions and methods for forming suchsilicon-containing films.

The present invention in one aspect relates to a group of halogen-freesilane or disilane derivatives that are substituted with at least onealkylhydrazine functional groups and can be used as CVD precursors fordeposition of silicon-containing thin films.

The silane derivatives of the present invention can be represented bythe general formula of:

wherein R₁ and R₂ may be the same as or different from each another andare independently selected from the group consisting of H, C₁-C₇ alkyl,aryl, and C₃-C₆ cycloalkyl, or R₁ and R₂ together may form C₃-C₆heterocyclic functional group with N, and wherein X, Y, and Z may be thesame as or different from one another and are independently selectedfrom the group consisting of H, C₁-C₇ alkyl, alkylamino, dialkylamino,and alkylhydrazido (e.g., R₁R₂NNH—, wherein R₁ and R₂ are same asdescribed hereinabove).

Preferably, X, Y, and Z are all identical functional groups. Morepreferably, X, Y, and Z are all C₁-C₇ alkyl, such as methyl or ethyl.Alternatively but also preferably, X, Y, and Z are all alkylhydrazido(e.g., R₁R₂NNH—, wherein R₁ and R₂ are same as described hereinabove),such as N,N′-dimethylhydrazido or N,N′-diethylhydrazido.

The disilane derivatives of the present invention can be represented bythe general formula of:

wherein R₁, R₂, R₃, and R₄ may be the same as or different from eachanother and are independently selected from the group consisting of H,C₁-C₇ alkyl, aryl, and C₃-C₆ cycloalkyl, or R₁ and R₂ together may formC₃-C₆ heterocyclic functional group with N, or R₃ and R₄ together mayform C₃-C₆ heterocyclic functional group with N, and wherein X₁, X₂, Y₁,and Y₂ may be the same as or different from one another and areindependently selected from the group consisting of H, C₁-C₇ alkyl,alkylamino, dialkylamino, and alkylhydrazido (e.g., R₁R₂NNH—, wherein R₁and R₂ are same as described hereinabove).

Preferably, the disilane derivative compound of the present invention ischaracterized by functional groups that are symmetrically distributed inrelation to the Si—Si bond.

Preferred silane or disilane derivative compounds of the presentinvention include, but are not limited to, Me₃Si(HNNMe₂), Si(HNNMe)₄,Me₂(HNNMe₂)Si—Si(HNNMe₂)Me₂, and(HNBu^(t))₂(HNNMe₂)Si—Si(HNNMe₂)(HNBu^(t))₂, wherein Bu and Me areconsistently used as the respective abbreviations of butyl and methylthroughout the text hereinafter.

Another aspect of the present invention relates to a method for forminga silicon-containing film on a substrate, comprising contacting asubstrate under chemical vapor deposition conditions including adeposition temperature of below 550° C., preferably below 500° C., andmore preferable below 450° C., with a vapor of a silane or disilanederivative compound that is substituted with at least one alkylhydrazinefunctional group.

Still another aspect of the present invention relates to a method ofmaking such silane or disilane derivative compounds, by reacting silaneor disilane compounds comprising one or more halogen groups (i.e.,halosilane or halodisilane) with alkylhydrazine in the presence of NEt₃,to substitute the one or more halogen groups of such silane or disilanecompounds with alkylhydrazine functional groups.

A still further aspect of the present invention relates to a method ofmaking Me₃Si(HNNMe₂), by reacting Me₃SiCl with approximately one molarratio of H₂NNMe₂ in the presence of NEt₃, according to the followingreaction:

A still further aspect of the present invention relates to a method ofmaking Si(HNNMe₂)₄, by reacting SiCl₄ with approximately four molarratio of H₂NNMe₂ in the presence of NEt₃, according to the followingreaction:

A still further aspect of the present invention relates to a method ofmaking Me₂(HNNMe₂)Si—Si(HNNMe₂)Me₂, by reacting Me₂(Cl)Si—Si(Cl)Me₂ withapproximately two molar ratio of H₂NNMe₂ in the presence of NEt₃,according to the following reaction:

A still further aspect of the present invention relates to a method ofmaking, by reacting (HNBu^(t))₂(HNNMe₂)Si—Si(HNNMe₂)(HNBu^(t))₂, byreacting (HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂ with approximately twomolar ratio of LiHNNMe₂, according to the following reaction:

Other aspects, features and embodiments of the invention will be morefully apparent from the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a STA plot for Si(HNNMe₂)₄.

FIG. 2 is an X-ray crystal structure of the compound Si(HNNMe₂)₄.

FIG. 3 is a STA plot for Me₂(HNNMe₂)Si—Si(HNNMe₂)Me₂.

FIG. 4 is a STA plot for (HNBu^(t))₂(HNNMe₂)Si—Si(HNNMe₂)(HNBu^(t))₂.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

The present invention relates to silicon precursors for CVD formation offilms on substrates, such as silicon precursors for forming low kdielectric films, high k gate silicates, low temperature siliconepitaxial films, and films comprising silicon, silicon oxide, siliconoxynitride, silicon nitride, etc., as well as to corresponding processesfor forming such films with such precursors.

Silane or disilane derivatives that contain one or more alkylhydrazinefunctional groups, free of any halogen substitutes, are foundparticularly suitable for low-temperature deposition of silicon nitridethin films, since the bond-strength of the nitrogen-nitrogen single bondin the hydrazine functional group relatively weak. Moreover, use of suchhalogen-free silicon precursors avoids the various problems involved inprevious CVD processes using hexachlorodisilane.

Preferred silane derivatives of the present invention can be representedby the general formula of:

wherein R₁ and R₂ may be the same as or different from each another andare independently selected from the group consisting of H, C₁-C₇ alkyl,aryl, and C₃-C₆ cycloalkyl, or R₁ and R₂ together may form C₃-C₆heterocyclic functional group with N, and wherein X, Y, and Z may be thesame as or different from one another and are independently selectedfrom the group consisting of H, C₁-C₇ alkyl, alkylamino, dialkylamino,and alkylhydrazido (e.g., R₁R₂NNH—, wherein R₁ and R₂ are same asdescribed hereinabove).

Preferred disilane derivatives of the present invention can berepresented by the general formula of:

wherein R₁, R₂, R₃, and R₄ may be the same as or different from eachanother and are independently selected from the group consisting of H,C₁-C₇ alkyl, aryl, and C₃-C₆ cycloalkyl, or R₁ and R₂ together may formC₃-C₆ heterocyclic functional group with N₁ or R₃ and R₄ together mayform C₃-C₆ heterocyclic functional group with N, and wherein X₁, X₂, Y₁,and Y₂ may be the same as or different from one another and areindependently selected from the group consisting of H, C₁-C₇ alkyl,alkylamino, dialkylamino, and alkylhydrazido (e.g., R₁R₂NNH—, wherein R₁and R₂ are same as described hereinabove).

Disilane derivative compounds that are substantially symmetrical instructure in relation to the Si—Si bond, i.e., all functional groups ofsuch compounds being symmetrically distributed in relation to the Si—Sibond, are particularly preferred for practicing of the presentinvention. For example, such disilane derivative compounds may containtwo identical alkylhydrazine functional groups and four identical C₁-C₅alkyl functional groups that are symmetrically distributed in relationto the Si—Si bond, such as Me₂(HNNMe)Si—Si(HNNMe)Me₂.

The silane or disilane derivative compounds as described hereinabove areadvantageously characterized by a vaporization temperature of less than300° C. Moreover, such compounds can be transported in vapor form atless than 300° C. and under atmospheric pressure, with no or little(<2%) residual material. The silicon-containing films that can be formedusing such disilane precursor compounds include Si₃N₄ thin films, high kgate silicates and silicon epitaxial films. In a particularly preferredembodiment of the invention, the films formed using such silane ordisilane precursors comprise silicon nitride.

Preferred silane or disilane compounds of the above-described formulasinclude, but are not limited to, Me₃Si(HNNMe₂), Si(HNNMe₂)₄,Me₂(HNNMe₂)Si—Si(HNNMe₂)Me₂, and(HNBu^(t))₂(HNNMe₂)Si—Si(HNNMe₂)(HNBu^(t))₂.

Synthesis and characterization of the above-listed preferred compoundsis described in the following examples:

Example 1 Synthesis and Characterization of Me₃Si(HNNMe₂)

A 3 L flask was filled with a solution comprising 2.5 L hexanes, 54.0grams (0.53 mol) NEt₃, and 30 grams (0.50 mol) of H₂NNMe₂. 58 grams(0.53 mol) Me₃SiCl, as dissolved in 500 mL of hexanes, was slowly addedinto the 3 L flask at 0° C. White precipitate was observed during theaddition of Me₃SiCl. After the completion of the reaction, the mixturewas warmed to room temperature, stirred overnight, and then filtered.The crude yield was in 80%. Regular distillation procedure was used topurify the end product, which has a boiling point of approximately 100°C. ¹H NMR(C₆D₆): δ 0.15 (s, 9H, —SiCH₃), 1.73 (br, 1H, —NH), 2.22 (s,6H, —NCH₃). ¹³C{¹H} NMR(C₆D₆): δ −0.54 (—SiCH₃), 52.4 (—NCH₃). Massspectrum: m/z 132 [M⁺], 117 [M⁺−Me)], 102 [M⁺−2Me)], 88 [M⁺−3Me)], 73[M⁺−(—HNNMe₂)].

Me₃Si(HNNMe₂) is a liquid at room temperature.

Example 2 Synthesis and Characterization of Si(HNNMe₂)₄

A 250 mL flask was filled with a solution comprising 200 mL hexanes,12.2 grams (120.7 mmol) NEt₃, and 7.25 grams (120.7 mmol) HNNMe₂. 5.0grams (29.4 mmol) SiCl₄, as dissolved in 15 mL of hexanes, was slowlyadded into the 250 mL flask at 0° C. White precipitate was observedduring the addition of SiCl₄. After the completion of the reaction, themixture was stirred overnight and then filtered at room temperature. Allvolatile materials were removed from the filtrate under vacuum. Thecrude yield was in 65% (5.0 g, 19.0 mmol). Purified end product wasobtained by recrystallization in hexanes at −5° C. ¹H NMR(C₆D₆): δ 2.42(s, 24H, —CH₃), 2.47 (br, 4H, —HN). ¹³C{¹H} NMR(C₆D₆): δ 52.7 (—CH₃).C₈H₂₈N₈Si. Found (calculated) C, 36.15% (36.34%), H, 11.02% (10.67%), N,42.66% (42.37%).

Si(HNNMe₂)₄ is a solid material having a melting temperature ofapproximately 73° C. The thermal stability of Si(HNNMe₂)₄ in solution at100° C. was monitored by proton NMR study for 7 days, and no significantdecomposition was detected.

FIG. 1 is a STA plot for Si(HNNMe₂)₄, indicating that Si(HNNMe₂)₄ can betransported completely with very little (<2%) residual material at 500°C.

FIG. 2 shows the X-ray crystal structure of Si(HNNMe₂)₄.

Example 3 Synthesis and Characterization of Me₂(HNNMe₂)Si—Si(HNNMe₂)M₂

A 3 L flask was filled with a solution comprising 2.5 L hexanes, 57grams (561 mmol) anhydrous NEt₃, and 50 grams (267 mmol) ofMe₂(Cl)Si—Si(Cl)Me₂. 34 grams (561 mmol) H₂NNMe₂, as dissolved in 100 mLof diethyl ether, was slowly added into the 3 L flask at roomtemperature. White precipitate was observed during the addition ofH₂NNMe₂. After the completion of the addition of H₂NNMe₂, the mixturewas stirred overnight, and then filtered. All volatile materials wereremoved from the filtrate under vacuum. The crude yield was in 86% (54g, 230 mmol). Vacuum distillation procedure was used to purify the endproduct, which has a boiling point of approximately 45° C. at 35 mTorr.¹H NMR(C₆D₆): δ 0.33 (s, 12H, —CH₃Si), 1.90 (br, 2H, —HN), 2.27 (s, 12H,—CH₃N). ¹³C{¹H} NMR(C₆D₆): δ −0.68 (—SiCH₃), 52.6 (—NCH₃). Massspectrum: m/z 175 [M⁺−(—HNNMe₂)], 132 [M⁺−(—HNNMe₂)−(—NMe₂)], 116[M⁺−(—SiMe₂(HNNMe₂)]. C₈H₂₆N₄Si₂. Found (calculated) C, 40.81% (40.98%),H, 10.99% (11.18%), and N, 23.67% (23.89%).

FIG. 3 shows the STA plot for Me₄Si₂(HNNMe₂)₂, which is a liquid at roomtemperature and can be transported in its vapor form completely withvery little (<1%) residual material at about 350° C. The thermalstability of Me₄Si₂(HNNMe₂)₂ in solution at 100° C. was monitored byproton NMR study for 7 days, and no significant decomposition wasdetected.

Example 4 Synthesis and Characterization of(HNBu^(t))₂(HNNMe₂)Si—Si(HNNMe₂)(HNBu^(t))₂

A 250 mL flask filled with a solution comprising 120 mL of hexanes and15.8 mL (1.6M, 25.3 mmol) of methyllithium ether solution. 1.52 grams(25.3 mmol) of H₂NNMe was slowly bubbled into the 250 mL flask at 0° C.Upon completion of the addition, the reaction flask was allowed to warmto room temperature and stirred for an additional hour. To this flask, a50 mL of diethyl ether solution containing 5 grams (12 mmol) of(HNBu^(t))₂(Cl)Si—Si(Cl)(HNBu^(t))₂ was slowly added at 0° C. Themixture was stirred overnight, and then refluxed for an additional fourhours. After it was cooled to room temperature, it was filtered. Allvolatile materials were removed from the filtrate under vacuum. Thecrude yield was in 72% (4.0 grams, 8.64 mmol). Purified end product wasobtained by recrystallization in hexanes at −20° C. ¹H NMR (C₆D₆): δ1.40 (s, 36H, —C(CH₃)₃), 1.55 (br, 4H, —HHC(CH₃)₃), 2.13 (br, 2H,—NHN(CH₃)₂), 2.43 (s, 12H, —NHN(CH ₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 34.3(—NHC(CH₃)₃), 49.5 (—NHC(CH₃)₃), 52.6 (—NHN(CH₃)₂). C₂₀H₅₄N₈Si₂. Found(calculated) C, 51.76% (51.90%), H, 12.14% (11.76%), N, 24.28% (24.21%).

FIG. 4 shows the STA plot for(HNBu^(t))₂(HNNMe₂)Si—Si(HNNMe₂)(HNBu^(t))₂, which is a solid at roomtemperature and can be transported completely with very little (˜0.03%)residual material at about 500° C.

Such silane or disilane derivative compounds as described hereinabovecan be used for low-pressure CVD deposition of varioussilicon-containing films, including silicon nitride thin films,consistent with the disclosure in U.S. patent application Ser. No.10/294,431 for “Composition and Method for Low Temperature Deposition ofSilicon-Containing Films Including Silicon Nitride, Silicon Dioxideand/or Silicon-Oxynitride” filed on Nov. 14, 2002, now U.S. Pat. No.7,531,679 issued May 12, 2009, the content of which is incorporated byreference in its entirety for all purposes.

While the invention has been described herein with reference to variousspecific embodiments, it will be appreciated that the invention is notthus limited, and extends to and encompasses various other modificationsand embodiments, as will be appreciated by those ordinarily skilled inthe art. Accordingly, the invention is intended to be broadly construedand interpreted, in accordance with the ensuing claims.

What is claimed is:
 1. A method of forming a silicon-containing film ona substrate, comprising contacting a substrate under vapor depositionconditions comprising a temperature below 450° C. with a vapor of adisilane compound of the formula:

to form said silicon-containing film on the substrate.
 2. The method ofclaim 1, wherein said film comprises silicon dioxide.
 3. The method ofclaim 1, wherein said film comprises silicon nitride.
 4. The method ofclaim 1, wherein said film comprises siliconoxynitride.
 5. The method ofclaim 1, wherein said film comprises a low dielectric constantsilicon-containing film.
 6. The method of claim 1, wherein said filmcomprises a gate silicate film.
 7. The method of claim 1, wherein saidfilm comprises an epitaxial silicon-containing film.
 8. The method ofclaim 1, wherein the substrate comprises a semiconductor devicesubstrate.
 9. The method of claim 1, wherein said vapor depositioncomprises chemical vapor deposition.
 10. The method of claim 1,conducted in an ULSI device fabrication process.
 11. The method of claim1, wherein said vapor is transported to said contacting at temperaturebelow 300° C.
 12. The method of claim 11, wherein said vapor istransported at atmospheric pressure.
 13. A method of manufacturing asemiconductor device, comprising using a silicon precursor of theformula:

to deposit at temperature below 450° C. a silicon-containing film on asubstrate for said semiconductor device.
 14. The method of claim 13,wherein the silicon precursor is used to form a silicon nitride materialin said semiconductor device.
 15. The method of claim 14, wherein saidsilicon precursor is used to form a semiconductor device diffusionbarrier layer.
 16. The method of claim 14, wherein said siliconprecursor is used to form a semiconductor device etch-stop layer.